U.S. Pat. No. 669,287 to Shilling discloses a horizontal boiler having longitudinal supporting brick work beneath the boiler wherein the brick contacts the sides of the boiler, thereby providing a space between the boiler and the brick. An asbestos or mineral wool filling is disposed in the space. The asbestos or mineral wool forms a cushion to counteract the expansion of the boiler and the supporting brick arch and to prevent flue dust from accumulating between the boiler and the brick work.
U.S. Pat. No. 169,977 to Firmenich et al. discloses a sectional boiler having rows of vertical tubes connecting a series of steam and water drums.